The present invention relates to a method and apparatus for controlling an automatically shifting transmission and, more particularly, to such a method an apparatus which simulates a driver's driving style and assures delivery of the demanded driving power from a consumption-oriented driving style to a power-oriented style.
Normally an automatic transmission control system is configured either to permit a method of driving that is as economical as possible or one that is as power-oriented as possible. Because of the characteristics of the Otto cycle engine, it is not possible to meet both criteria simultaneously. Frequently, a compromise therefore has to be made between both extremes since a purely consumption-oriented shifting program does not offer sufficient safety reserves in critical traffic situations, and the fuel consumption is too high in the case of a power-oriented shifting program.
Another possibility is a manual change-over between an "economy program" and a "power program", (Automobiltechnische Zeitschrift, Volume 6/1983, pp. 401-405). In this case, the driver must first actuate a change-over switch before the corresponding shifting program is made available. Two alternative extremes are now offered to the driver which, however, permit either only a method of driving that is consumption-oriented or one that is power-oriented.
It is also known from the DE-PS 33 41 652 to automate this manual change-over. To this end, an accelerator pedal signal which is proportional to the position of the accelerator pedal is sensed and stored. By virtue of the sensed accelerator pedal signal value, accelerator pedal signal values which were detected and stored earlier are continuously updated, and an accelerator pedal activity is calculated from the stored accelerator pedal signals which evaluates a driver's driving style or a driving situation. This accelerator pedal activity will then be used for influencing limit values of shifting decisions in such a manner that the transition from the consumption-optimized to the power-optimized shifting program takes place continuously.
It is therefore possible to simulate the driver's driving style by way of this control system by detecting a quantity which is representative of this driving style. It was found, however, that in certain driving situations, for example, on routes with many bends, the driving style or a driving situation cannot be simulated by this system to a desirable extent.
It is therefore an object of the present invention to provide a method and apparatus for controlling an automatically shifting transmission that avoids the above-mentioned disadvantages.
This object has been achieved in accordance with the present invention by providing a method and apparatus which, in addition to a sensed throttle valve signal value, senses at least one additional cyclically and/or non-cyclically sensed operating parameter of the motor vehicle.
Principal advantages of the present invention are that a method and apparatus for the control of an automatically shifting transmission are provided which, based on a shifting program that is as consumption-optimal as possible, dynamically adapts itself to vehicle handling and the just-existing or real time driving or traffic situation without the requirement of actuating additional operating elements. These advantages have been achieved through only a slightly higher expenditure of operating or driving parameters to be detected by sensors so that an already existing transmission control device for an electrohydraulic transmission, such as model 4HP22 of ZF Co., can be used as part of the present invention without any major expenditures. In addition to only a single additional sensor, only a change of the control method is this required.
As a result, a drive of a motor vehicle which is equipped with the apparatus and control system of the present invention for the automatically shifting transmission which operates according to the method of the present invention is always ensured of receiving the respective driving power which it demands, in which case, care is taken that the fuel consumption is always as low as possible in all ranges.